Fig. 7

CVHR associated with sleep apnea episodes in a representative patient with normal vagal reflex function (A) and a patient with moderately impaired vagal reflex function (B). The blue bars indicate the temporal location of the dip in the R-R interval caused by CVHR. Airflow detected by mouth-nose thermistor shows intermittent apnea or hypopnea in both patients, but the response of the R-R interval, or CVHR, is blunted in patient B compared to patient A. This is reflected in the difference in the amplitude of the CVHR (Acv), 3.4 vs. 5.3 ln (ms)